As optical discs such as a write-once digital versatile disc (DVD-R), etc., optical discs having an ink receiving layer (printing layer) on their labeling side (a side opposite to the side on which laser light is irradiated during recording or reproduction of optical information) are in use in practice. Users can print pictures or drawings on the printing layer using an ink jet printer, etc.
Procedures for printing an image using an ink jet printer, etc. are advancing day by day, and image quality obtained has become exceptional. On the other hand, however, providing a new ink jet printer, etc., for forming an image is costly. Furthermore, transferring an optical disc to an ink jet printer, etc. to form an image thereon, after recording information on the optical discs, takes time and effort. The task seems to be more complicated where information is recorded on plural optical discs and images are formed therefrom. Furthermore, when a printing layer is provided on the surface of the optical disc, there is a fear that problems of storability, such as deterioration due to moisture in the air, stains due to adhesion of dusts, etc., may arise.
Image forming apparatuses and methods for forming an image that can record an image having a high contrast ratio on an optical disc as well as recording information on the recordable side have been suggested (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2004-005848). Furthermore, several optical recording media on which an image can be formed by irradiation of laser light are known (for example, see JP-A Nos. 2000-113516, 2001-283464 and 2000-173096). These are convenient in that they can form good visible images. However, it is impossible to recognize on which side of an optical disc an image can be formed. Furthermore, quality control, etc. may become difficult since these optical discs do not comprise supplemental information, such as image forming information, etc.
Therefore, there is a need for an optical disc in which a side on which image forming is carried out and a side on which image forming is not carried out can be easily distinguished and quality control thereof is easy. Furthermore, there is a need for an image forming method, which is suitable for image forming on such an optical disc.